DC-DC converter with reduced ripple

Abstract

A DC/DC converter is provided which can be produce easily and inexpensively with an alternating current component with which a superimposed direct current is reduced in an output voltage (ripple). A C+DC/DC converter includes an input and output, a series arm which is arranged between the input and the output and in which at least one first inductor and first capacitor are arranged, and a capacitor arranged in a first shunt arm at the output. A second shunt arm arranged parallel to the first shunt arm is equipped with a first switch and a second switch arranged in series and a second inductor such that the first connection of the inductor is connected to a point between the first inductor and the first capacitor and the second connection of the inductor is connected to a point between the first and the second switch.

What is claimed is: 
     
       1. A DC/DC converter comprising:
 an input and an output, 
 a longitudinal arm arranged between the input and the output and having at least a first inductor and a first capacitor, 
 a first shunt arm connected across the output, 
 a second shunt arm having a first active semiconductor switch and a second active semiconductor switch and forming a serial circuit having two end connection points which are connected directly to respective terminals of the output, and a center connection point, wherein a terminal of the first active semiconductor switch facing away from the second active semiconductor switch is connected directly to a terminal of the first capacitor of the longitudinal arm and is connected directly to the output, and 
 a second inductor having a first terminal connected to a point between the first inductor and the first capacitor and a second terminal connected to the center connection point, and 
 a controller providing control signals to the first and second active semiconductor switches such that the first and second active semiconductor switches are activated alternately, closing the first active semiconductor switch is when the second active semiconductor switch is opened and vice versa, wherein the input and the output are interchangeable, thereby allowing bi-directional operation of the DC-to-DC converter. 
 
     
     
       2. The DC-to-DC converter according to  claim 1 , wherein the first and second active semiconductor switches are a BJT (Bipolar Junction Transistor), a MOSFET (Metal-Oxide-Semiconductor Field-Effect-Transistor) or an IGBT (Insulated Gate Bipolar Transistor). 
     
     
       3. A DC/DC converter comprising:
 an input having an applied input voltage with a first polarity, 
 an output generating an output voltage with a second polarity, 
 a longitudinal arm arranged between the input and the output and having a first inductor and a first capacitor, 
 a first shunt arm connected across the output, 
 a second shunt arm connected parallel to the first shunt arm and having a second active semiconductor switch and a second inductor connected in series, wherein a terminal of the second active semiconductor switch facing away from the second inductor is connected directly to the output, and a first active semiconductor switch having a first terminal connected to a point between the second active semiconductor switch and the second inductor and a second terminal connected to a point between the first inductor and the first capacitor, 
 wherein the second polarity is inverted with respect to the first polarity. 
 
     
     
       4. The DC-to-DC converter according to  claim 3 , wherein the first and second active semiconductor switches are a BJT (Bipolar Junction Transistor), a MOSFET (Metal-Oxide-Semiconductor Field-Effect-Transistor) or an IGBT (Insulated Gate Bipolar Transistor). 
     
     
       5. A method for operating a DC-to-DC converter, comprising:
 connecting a first inductor and a first capacitor in series between an input and an output of the DC-to-DC converter, 
 connecting a first shunt arm across the output, 
 forming a second shunt arm of a serial circuit consisting of a first active semiconductor switch and a second active semiconductor switch, the serial circuit having two end connection points, which are connected directly to respective terminals of the output, and a center connection point, wherein a terminal of the first active semiconductor switch facing away from the second active semiconductor switch is connected directly to a terminal of the first capacitor and is connected directly to the output, 
 connecting a first terminal of a second inductor to a point between the first inductor and the first capacitor and connecting a second terminal of the second inductor to the center connection point, and 
 alternately activating the first and second active semiconductor switches such that the first active semiconductor switch is closed when the second active semiconductor switch is opened and vice versa, 
 further comprising interchanging the input and the output and performing bi-directional operation of the DC-to-DC converter. 
 
     
     
       6. The method of  claim 5 , wherein the first and second active semiconductor switches are a BJT (Bipolar Junction Transistor), a MOSFET (Metal-Oxide-Semiconductor Field-Effect-Transistor) or an IGBT (Insulated Gate Bipolar Transistor). 
     
     
       7. A method for operating a DC-to-DC converter, comprising
 connecting a first inductor and a first capacitor in series between an input and an output of the DC-to-DC converter, 
 connecting a first shunt arm across an output, 
 forming a second shunt arm of a serial circuit consisting of a second inductor and a second active semiconductor switch, 
 connecting a terminal of the second active semiconductor switch facing away from the second inductor directly to the output, 
 connecting a first terminal of a first active semiconductor switch to a point between the second active semiconductor switch and the second inductor, 
 connecting a second terminal of the first active semiconductor switch to a point between the first inductor and the first capacitor, 
 applying to the input an input voltage with a first polarity, and 
 generating at the output of the De-to-DC converter an output voltage with a second polarity that is inverted with respect to the first polarity. 
 
     
     
       8. The method of  claim 7 , wherein the first and second active semiconductor switches are a BJT (Bipolar Junction Transistor), a MOSFET (Metal-Oxide-Semiconductor Field-Effect-Transistor) or an IGBT (Insulated Gate Bipolar Transistor).